Explore Scientific Triplet ED APO 102mm too slow for astrophotography?

[maxchess]

Hi

I am looking to upgrade my scope and I am tempted by the ES 120. I intend to use it for Astrophotography.

I currently have a cheap Aquilla frac 90mm f5 fl 500, on a Heq 5 pro, mounted on a steel pier set in concrete. I use a Canon 450d but will upgrade later. The Aquilla cost £175 and I have got some great results, but I suspect/hope upgrading will give me big improvements. I also have a C8.

My reasoning went Sw80ed great reviews, but doublet, ES80ED is triplet, but for a little more I could get the ES120 essential triplet. 1.6 more light. But it's f7 a bit slow and it's fl is 714, maybe a bit tight FOV?

Any views!, plus what difference will I notice?

 

[gonzostar]

I have the ES102 (f7) APO and have used it with the canon 450d, on a AVX  mount. I have being very happy with results. I use this set for DSO's and i have a c8 with is for lunar and planets 

There is a link in resources if you want to check FOV with various set ups

Cheers

Dean

[Craney]

"......maybe a bit tight FOV? "

There might be a 0.85x or 0.7x  focal reducer / field flattener  available for this model.

[vlaiv]

46 minutes ago, maxchess said:

Hi

I am looking to upgrade my scope and I am tempted by the ES 120. I intend to use it for Astrophotography.

I currently have a cheap Aquilla frac 90mm f5 fl 500, on a Heq 5 pro, mounted on a steel pier set in concrete. I use a Canon 450d but will upgrade later. The Aquilla cost £175 and I have got some great results, but I suspect/hope upgrading will give me big improvements. I also have a C8.

My reasoning went Sw80ed great reviews, but doublet, ES80ED is triplet, but for a little more I could get the ES120 essential triplet. 1.6 more light. But it's f7 a bit slow and it's fl is 714, maybe a bit tight FOV?

Any views!, plus what difference will I notice?

 

Don't think in terms of slow scopes for AP.

What you should be thinking is resolution at aperture. Canon 450d has 5.2um pixels (I believe) and at 714mm focal length it will give you 1.5"/pixel.

1.5"/pixel is quite good resolution for AP, so you will be happy there. It will not do very wide field (you will need at least 4 panels for Andromeda for example), but it will give you decent resolution on most DSO-s.

[michael.h.f.wilkinson]

F/7 shouldn't be a problem, especially if you add a reducer. Add a 0.8x reducer and you have an F/5.6 combination, giving about 2" per pixel, and 36% shorter exposure times, and more FOV.

[xtreemchaos]

don't let a long FL put you off, you adapt to them, I use a F11 frac nearly all the time, I had to do a 3 pane mosaic to get all the great orion neb last winter but where the long scope wins is with small stuff, if I want wide I use the cannon and lens. goodluck. charl.

[michael8554]

If you think the fov is too tight (and that's for you to decide) then buy a different scope.

Makes no sense to me to lash out on a scope and then have to buy a recucer to make it suitable.... ?

Michael 

[maxchess]

Ok all that is really useful input and I guess there is no one size fits all. But is the ED APO 102mm “good quality” and what does that mean? I would hope not to buy another scope after my next purchase but try and improve my technique through guiding, better focus, filters etc. Then maybe in a years time go for a dedicated Astro camera. With this scope will I be building on a firm foundation or will I be wishing I had bought something else.

[Stub Mandrel]

I was looking at someone's (excellent) images on Friday. They were complaining that their short FL scope means things like galaxies and planetary nebulas come out tiny.

You can't have it both ways! Either have more than one scope, use barlows/focal reducers or just get a scope that suits your usual choice of object. As you already have a C8 for the smaller objects, I'd go for are short FL scope if I were you.

I mostly image with 130P-DS 580mm (with coma corrector) and a 150PL (1200mm), but will be adding a 66ED at about 400mm soon for larger objects as a step up from a 400mm tele lens which has excessive CA.